P886Comparison of applanation tonometry-derived carotid-femoral pulse wave velocity and echo-tracking derived one-point carotid pulse wave velocity in a group of normal subjects.


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Abstract

Background: Great emphasis has been placed on the role of arterial stiffness in the development of cardiovascular disease (CV). To date the applanation tonometry derived carotid-femoral pulse wave velocity (PWV) is considered the gold standard in this field. Recently echo-tracking derived measures of arterial stiffness have been introduced in clinical practice, allowing the assessment of one-point PWV. Little is known however about the relations between carotid-femoral PWV and one-point PWV.Methods: A group of 72 consecutive asymptomatic subjects (47 males, 25 females, mean age 49±14 years, range 16-90 years), free of overt CV were studied. Carotid-femoral PWV was calculated as is the distance traveled by the wave divided by the time for the wave to travel that distance using a Sphygmocor system (ArtCor, Sydney, Australia), with a single high fidelity applanation tonometer (Miller). Carotid ultrasound study at the level of the left common carotid artery before the bifurcation (using a high definition echo-tracking system implemented in a Prosound Alfa10 Aloka machine, Japan) was performed. One-point carotid PWV was calculated as √βxPd/2ρ where β=ln(Ps/Pd)/[(Ds-Dd)/Dd]. Ps is systolic blood pressure, Pd is diastolic blood pressure, Ds is maximal arterial diameter and Dd is minimum arterial diameter; ρ is blood density (ρ=1.050 Kgxm-3).Results: There was a systematic underestimation of carotid-femoral using one point PWV (mean values of carotid-femoral PWV 7.2±1.9 m/s, one point PWV 5.7±1.1 m/s). Carotid-femoral PWV and one-point PWV correlated significantly each other (r= 0.37; p=0.002). Both indexes were correlated with age (respectively r= 0.64 and r=0.56, p<0.0001 for both). Only one-point PWV correlated significantly with body mass index (r=0.31, p=0.008), while carotid-femoral PWV did not (r=0.19, p=0.094).Conclusions: Our study shows that one-point PWV, measured at carotid level using echo-tracking technique, is correlated with but underestimates systematically the traditional carotid-femoral PWV in normal subjects. Both indexes of stiffness are strongly related with age but 1-point PWV seems to be better related with obesity. The knowledge of these findings could be relevant in order to use echo-tracking measures in clinical practice.

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